Presently in the art of dispensing liquids and gels, it has become desirable to dispense such liquids and gels in the form of a foam. Typically, the foam is generated from combining a liquid or gel material with air in a forceful way, with the combination of air and the liquid or gel then being extruded through a screen, mesh, sponge or the like to obtain a foam of substantially uniform bubbles.
The invention herein will be discussed with regard to soap foam dispensers, in which liquid soap and air are combined as described for achieving the requisite foam. However, it will be appreciated that the concepts of the invention may be extended to the generation of foam from other liquids, gels, and the like, including those of alcohol-based sanitizers. Presently, soap foam is generated in a variety of ways, most of which require the depositing of a quantity of liquid soap in one chamber, an amount of air in another chamber, and compressing the two chambers to forcefully drive liquid and air to a foam generator for the generation of the foam. Such activities require significant mechanical movement, typically employing a pair of pistons, one for liquid and one for air, to drive the separate quantities to the foam generating member. Typically, these dual chambered pumps are an integral portion of disposable containers and add significantly to the cost of such containers. Moreover, being of a mechanical nature, the pumps are not given to excessive use and are typically designed to have a useful life only slightly exceeding the number of dispensing cycles available from the container.
A system is disclosed in Published U.S. Patent Application No. 2010/0102083 having a permanent compressor that is adapted to communicate with replaceable containers to drive both a foamable liquid and air from within the container to a foam generator to form a foam product. A foam dispenser includes a housing that receives a refill unit having a container with an interior containing foamable liquid and air. An air compressor, which is a more permanent part of the dispenser housing, selectively communicates with the air in the container and is employed to inject air into the container so as to increase the pressure therein. An air tube communicates with the air within the container, while a liquid tube communicates with the liquid in the container. Each tube communicates with the container through a plug seal and extends from communication with the container to a dispensing head. Separate valves communicate with each tube such that the tubes can be shut-off so that the container can be pressurized. Once the container is pressurized to a desired dispensing pressure, the valves associated with the liquid and air tubes are opened so that a portion of the foamable liquid and a portion of air are advanced to a foam generator wherein the air and liquid are mixed to create and dispense the foam product.
A pressure sensor and a vent valve are provided as part of the refill unit and communicate with the container so that, in the event that the pressure within the container becomes too large, the vent valve can open to prevent undesired consequences. For example, in the event of a malfunction, it might be possible for the pressure generated by the compressor to burst the container. Also, in the event that the pressure in the container is allowed to become too large (i.e., greater than the desired pressure) it is possible that the air and liquid would be advanced to the foam generator at an undesirably large pressure, leading to an undesired dispensing.
Different methods are proposed for employing the foam dispenser. In one embodiment, the dispenser receives a dispensing request from an individual using the dispenser and, upon receipt of that dispensing request, generates the desired pressure, thereafter opening the valves to permit the dispensing of foam. In a separate method, the dispenser constantly works to establish the desired dispensing pressure in the container such that, when a user places their hands at the appropriate location for a dispensing request, the container is already at the desired dispensing pressure, and valves simply need to be opened to cause the dispensing of product as foam.
The present invention improves upon the invention disclosed above. In the prior invention, the refill units include air and liquid tubes that each communicate with the container through their own separate and distinct plug. Similarly, the compressor, the pressure sensor and the vent valve all separately and distinctly communicate with the contents of the container through one of the container walls. It will be generally understood in the art that these refill units, once empty of product, must be replaced, the dispenser housing being a more permanent structure that simply receives refill units when necessary to replace older units. Employing the structure proposed in the aforementioned publication presents a number of problems in that each plug, sensor and valve that communicates with the container of the refill unit presents a potential area for leakage, thus frustrating the generation of the desired pressure. Also, associating the vent valve and sensor with the container of the refill unit is undesirable inasmuch as the refill unit (and container thereof) is thrown away and replaced when empty. Throwing away the refill unit results in throwing away the vent valve and sensor and thereby increases the cost of the refill unit. As seen in the publication, the air and liquid tubes are plugged into the container at the top thereof such that the tubes are quite long and must be appropriately guided through the structures of the dispenser housing in order to communicate between the top of the container and the outlet area of the dispenser housing. Realizing these problems with the prior publication, the present invention provides a number of structural advancements.